erro SigninComponet_Host.ngfactory.js? [sm]:1 ERROR TypeError: Cannot read property 'nativeElement' of undefined at SigninComponet.ngOnInit

Boa tarde, Renato! Como vai?

Essas duas linhas não são removidas. Vc poderia colar aqui o conteúdo completo do arquivo signin.component.ts?

Qualquer coisa é só falar!

Grande abraço e bons estudos, meu aluno!

Olá, Gabriel bom dia.

/* Primeiramente precisamos injetar uma variável de template referente ao campo desejado. Esta variável ao ser injetada será do tipo ElementRef. Após isso teremos acesso ao método focus() */ import { Component, OnInit, ViewChild, ElementRef } from '@angular/core'; import { FormGroup,FormBuilder, Validators } from '@angular/forms'; //import { AuthService } from 'src/app/core/auth/auth.service'; import { AuthService } from '../../core/auth/auth.service'; import { Router } from '@angular/router';import { PlatformDetectorService } from 'src/app/core/platform-detector/platform-detector';

@Component({ templateUrl:'./signin.component.html' }) export class SigninComponet implements OnInit{ loginForm:FormGroup;

/*No Angular 8, o ViewChild usa 2 parâmetros 
https://angular.io/api/core/ViewChild*/
@ViewChild('userNameInput', {static: false}) userNameInput: ElementRef<HTMLInputElement>;

constructor(
    private formBuilder: FormBuilder,
    private authService: AuthService,
    private router: Router,
    private platformDetectorService: PlatformDetectorService){}

ngOnInit(): void {
    this.loginForm = this.formBuilder.group({
        userName: ['', Validators.required],
        password:['', Validators.required]
    });
    this.platformDetectorService.isPlatformBrowser() && 
    this.userNameInput.nativeElement.focus();
}
login(){
    console.log('vai se autenticar')
    const userName = this.loginForm.get('userName').value;
    const password = this.loginForm.get('password').value;

    this.authService
    .authenticate(userName, password)
    .subscribe(
    () => this.router.navigate(['user', userName]),
        err => {
            console.log(err);
            this.loginForm.reset();
            this.platformDetectorService.isPlatformBrowser() &&
            this.userNameInput.nativeElement.focus();
            alert('Invalid user name or password');
        }
    );
}

}